You might use some plexi-glass, or even saran wrap to cover part of the cage top, to keep the humidity higher. It will keep most species more active, but you can get by without this, if you mist heavily, 1-2 times a day. Give them a nice shallow water dish, fill it with water that does not smell of chlorine. Actually, bottled spring water is best. And do not use the reverse osmosis water; it is very clean, and great for reptiles to drink, but amphs. cannot regulate it properly, because of the removal of the mineral solids. So............basically the frogs take in too much water, and it can kill them. Only fill the water bowl to about their vent, or half way up their throat, to be on the safe side. And..........if possible, try to put some type of artificial plant or cover over the pool, as the frog will feel more secure. ( See the thread about Chubby frogs). Substrate...........either just spaghnum moss, or the potting soil and peat mix that many use for their T's, just don't put any more dirt than 2 inches deep. They love to burrow in wet spagh. moss, so you could put that on top of the dirt.
I am not really shure if I am getting the Tomato frog or not.I was just considering maybe adding one of these little guys to my list of animals I was going to be looking for at my next local reptile expo(Was gonna look for a second scorp species,some millipedes and maybe a frog)
About the humidity...........most info. says 70-80 percent. In my exp., it is just too difficult to recreate the natural conditions of Madagascar, in a home terrarium. In a cage, without the natural filtering systems of the jungle, too high of a humidity can cause many problems, such as mold and fungus, or make the production of bacteria much more likely. So.........I would just try for about 70% humidity, and mist once a day, very heavily. This will simulate the jungle rains that occur daily in their habitat, and keep them active. If they stay burrowed down all the time; it is too dry, and you will have to mist twice a day. But........generally, once a day is fine, and it allows the humidity to stay high for a time, and gradually taper off, to prevent any problems with excess humidity. And ............if they feel the need to be more humid, they can always take a bathe! It's actually very easy to regulate the humidity, once you watch the frog for awhile.